JPAã«ã¯é常ã«æå¾ ãã¦ãã人ãå¤ãã§ããããç§ããã®ä¸äººã§ããå®éã«ããã¸ã§ã¯ãã§ä½¿ã£ã¦ã¿ã¦ãè¦ãã¦ããåé¡ç¹ãæ¸ãã¦ã¿ã¾ããJPAã®å®è£ ã¨ãã¦ã¯ï½¤Hibernate3.2ã使ã£ã¦ãã¾ãã å¦ç¿ã³ã¹ããé«ãã JPAã®å ¨æ©è½ã®ãã¡ï½¤ããã¸ã§ã¯ãã§ä½¿ããã®ã«çµãè¾¼ãã§æè²ããã¨ã3æ¥ç¨åº¦ã§æãããã¨ãã§ããã®ã§ãã、ãããã使ããããã«ãªãã«ã¯ï½¤2ã4é±éãããã¾ããããã¯ãHibernate in Actionã«ãæ¸ãã¦ããã®ã§ãããããã®ãªãã§ãããã ãã©ãã«ã·ã¥ã¼ãã£ã³ã°ãé£ããã å¤ãã®ããã¸ã§ã¯ãã§å®éã«ããã«ã®ã¯ããã§ãããããã¡ã®ããã¸ã§ã¯ãã§ã¯ï½¤Hibernateè·äººã§ããå°æãããããã«ããããããããããè¦å´ãã¾ãããHibernateè·äººã®ããªãããã¸ã§ã¯ãã§ä½¿ãã®ã¯å³ããã®ã§ã¯ãªããã¨æãã¾ãã SQLã®æ±ãã貧弱ã JPQLã¯ãSQLã®ããªã貧弱ãªãµãã»ãããªã®
OutOfMemoryErrorã®ä¸»ãªè¦å ä¾ã¨ãã¦ãDBMSãããã¼ã¿ãåå¾ããããããã¾ãã LASYãã§ããã«ããN + 1 åé¡ãåé¿ããããã«ãçµåå ãã¼ãã«ã®è¦ç´ ãä¸æ°ã«æã£ã¦ããJOIN FETCHã使ã£ãã¨ãããå¼ãæãã«Javaãã¼ã使ç¨éãå¤ããªãã®ã¯ããããã±ã¼ã¹ã§ãã 以ä¸ã®ãããªã1ã¤ã®Issueã«å¯¾ãã¦è¤æ°ã®IssueAttributeãæã¤1対å¤é¢é£ã®ã¨ã³ãã£ãã£ã®æä½ãä¾ã«ãOutOfMemoryErrorãå°ãã§ãé¿ããæ¹æ³ãèãã¦ã¿ã¾ãã @Entity public class Issue implements Serializable { private static final long serialVersionUID = 1L; @Id @GeneratedValue private int issueId; private String tit
JPAï¼Java Persistence APIï¼ã¯ããã¼ã¿ãã¼ã¹ããåå¾ãããã¼ã¿ãã¡ã¢ãªä¸ã«ä¿æããä»æ§ã«ãªã£ã¦ããã ãã®ãããä¸ç¨æã«å¤§éã®ãã¼ã¿ãåå¾ããã¨ãã¡ã¢ãªå®¹éãå§è¿«ãã¦ãã¾ããææªã®å ´åã¯OutOfMemoryErrorãèµ·ããå¯è½æ§ãããã æ¬ç¨¿ã§ã¯ãJPAã®æ¨æºæ©è½ããã³ãã¤ãã£ãæ©è½ã®ããããã«ã¤ãã¦ãã¡ã¢ãªä½¿ç¨éãæããªãã大éãã¼ã¿ãåå¾ããæ¹æ³ã¨ããã¤ãã£ãæ©è½ããã¾ãåä½ããªãå ´åã®åé¿çãç´¹ä»ããã JPAã¯èªã¿è¾¼ãã ãã¼ã¿ãä¸æ¬¡ãã£ãã·ã¥ã¨ãã¦ä¿æãã JPAã¯ãèªã¿è¾¼ãã EntityãPersistenceContextï¼æ°¸ç¶åã³ã³ããã¹ãï¼ã¨å¼ã¶é åã§ç®¡çããã ããã«æ ¼ç´ãããç¶æ ãä¸æ¬¡ãã£ãã·ã¥ã¨å¼ã³ãä¸æ¬¡ãã£ãã·ã¥ãããEntityãManagedãªç¶æ ï¼JPAã«ç®¡çãããç¶æ ï¼ã¨å¼ã¶ï¼ãªããäºæ¬¡ãã£ãã·ã¥ããããå²æããï¼ã Persist
Summary: Nested | Field | Constr | Method Detail: Field | Constr | Method
JpaRepositoryã§ã¯ãã¡ã½ããåã®åã¥ãæ¹ãããããã°ãå¿ è¦ãªã¡ã½ãããããã£ã¨æ¸ãã¦è¿½å ã§ãã¦ãã¾ãã¾ããå¦çã¯ä¸åå¿ è¦ãªãããã ã¡ã½ããã®å®£è¨æãæ¸ãã ãã§ãããã ãããããããã決ããããã«ã¼ã«ã«å¾ã£ã¦ãã¡ãã¨ã¡ã½ããåãã¤ãã¦ããã°ãã§ããé©å½ã«åã¥ããã ãã§ã¯ãã¡ã½ããã¯èªåçæãããªãã®ã§ãã ã§ã¯ãã©ã®ãããªå½¢ã§ã¡ã½ããåãã¤ããã°ããã®ã§ãããããããã§ãã®å½åè¦åã«ã¤ãã¦ç°¡åã«æ´çãã¦ããã¾ãããã âfindByââ åºæ¬ã¯ãããã§ãããfindByãã®å¾ã«ã¨ã³ãã£ãã£ã®ããããã£åãç¶ãã¦è¨ãã¾ãããã®ããããã£åã¯ãæåã®ï¼æåç®ã¯å¤§æåã«ãã¾ããä¾ãã°ãnameããæ¤ç´¢ãããªããfindByNameãã§ãããmailããæ¢ããªããfindByMailãã¨ãªãããã§ãã ãã以éã¯ããã®åºæ¬å½¢ã§ãããfindByââãã®å¾ã«ç¶ãã¦æ¸ããã®ã«ãªãã¾ãã âL
The document discusses Spring Data JPA and entity relationship mappings. It provides examples of mapping entities with relationships like OneToMany and ManyToOne using annotations. It also demonstrates various JPA operations like persisting, updating, deleting entities and querying relationships with examples of the generated SQL.Read less
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